She portrayed Mo'at in the Avatar franchise, Amanda Waller in various DC media, and Claudette Wyms in the FX police drama series The Shield (2002–2008).

Pounder portrayed Dr. Angela Hicks in the medical drama series ER (1994–1997), Irene Frederic in Warehouse 13 (2009–2014), and District Attorney Tyne Patterson in Sons of Anarchy (2013–2014).

In film, she appeared in All That Jazz (1979), Go Tell It on the Mountain (1984), Prizzi's Honor (1985), Bagdad Cafe (1987), Postcards from the Edge (1990), Psycho IV: The Beginning (1990), Benny & Joon (1993), Demon Knight (1995), Face/Off (1997), End of Days (1999), Orphan (2009), Avatar (2009), The Mortal Instruments: City of Bones (2013), and Godzilla: King of the Monsters (2019).

[3] Her mother Betsy Enid Arnella (nee James) worked at the United States Embassy while the family lived in London, England.

[5] She matriculated at Hastings College of Arts and Technology where Pounder studied painting, but dropped out as a freshman after moving to the United States.

[8] She continued her career in New York City theater,[9] where she appeared in The Mighty Gents by playwright Richard Wesley, and Open Admissions on Broadway.

She then returned to guest appearances on other shows, including The Practice, Law & Order: Special Victims Unit, Millennium, The West Wing (where she was considered for the role of C. J. Cregg), and the short-lived sitcom Women in Prison.

She has also lent her voice to several video games and animated projects, including Aladdin and the King of Thieves, True Crime: Streets of LA, Gargoyles as Desdemona and Coldfire, and Justice League Unlimited as government agent Amanda Waller, which role she reprised for the animated film adaptation of the comic book Superman/Batman: Public Enemies[13] as well as the video game Batman: Arkham Origins, its sequel Batman: Arkham Origins Blackgate, and another animated film that takes place in continuity with the games, Batman: Assault on Arkham.

[15] In an interview, she said about the pandemic: "When it's this massive disease, and it's affecting things in 5,000 different ways, it requires great strength and power—and there is power in numbers.